Pulled head stud... helicoil?

I have a pulled head stud on a Subaru EJ25 and I need some advice.

Current route I plan to take is to have a machine shop helicoil the bad stud.

I'll then use an ARP stud kit instead of threading the OEM bolts back in.

What does everyone think? Will it hold?

This is for my daily appliance 2000 Subaru Forester N/A.

Personally for something like this, I would use a Time-Sert. It is like a Heli-Coil, but on steroids.

Brian

If the machine shop does its job well, there will be no problem. They'll know to keep the insert and threads square with the world; it will last at least as well as the stock bolts.

OTOH, if you turbo it and bump the boost to 45#, don't come cryin' to me!

I like this idea.

http://www.timesert.com/

Regular kits on Amazon look reasonable. This might come together after all.

Yes, Time-sert is what you want. They're holding the exhaust manifold in place on my rallycar.

A helicoil is better than the original thread, and very simple to install No need to over think it.

I am with Zomby woof on the helicoil, it is fine for a NA daily. Timesert = magnesium porsche case or a race car. You don't need the shop, its a do it your self project.

+3 on Helicoil. Most alum aircraft parts have helicoils in them. Timeserts are great for parts where the hole has become to big for helicoils due to bad removal of the broken OEM.

Weellll, OK, but the helicoils pulled right out, and we replaced em with timeserts.

Helicoils definitely have a tendency to pull out sometimes.

Keenserts are not particularly expensive and I've had absolutely awesome luck with them. I think McMaster Carr has them. Nicest part about the keenserts is that they go in w/o any special tools (just a drill, tap and a screwdriver or allen key). Downside is they need a bigger hole than a helicoil does.

Helicoils, if properly done, definitely DO NOT have a tendency to pull out. If yours are pulling out, you have something wrong

is that an aluminum block? HTS-2000? youtube it

Zomby woof wrote: Helicoils, if properly done, definitely DO NOT have a tendency to pull out. If yours are pulling out, you have something wrong

No doubt, but I'll take foolproof and reliable over foolvulnerable and reliable, because I'm a fool.

Pumpkin Escobar wrote: is that an aluminum block? HTS-2000? youtube it

i just saw that video a couple weeks ago and holy crap does it look impressive! have you used it yet?

no, but I have A LOT of ideas!

Being a machinist in the aerospace industry I'd be comfortable with a helicoil. If properly installed they are stronger than a regular tapped hole. Basicly the same as a rolled thread bolt is stronger than a cut thread bolt. Now if you like overkill go with a keensert. It's like the Timesert only with keeper tangs. The car will rust to nothing and zombies will take over the earth before a keensert will come out.

Just finishing the thread.

I used the Timesert. There was no way to thread a helicoil 3" down into the block.

You have to file/grind the flange off the end of the timesert. That's used for flush holes and if you leave it on it will get stuck part way down the tapered hole (thanks Subaru!).

Instead of using the Timesert insert tool you have to use an old head bolt. That will allow you to drive that insert down into the hole without having the end expand too soon. Mark the end of the head bolt so you know how far in it needs to go. Finish up with the Timesert insert tool which will expand the end of the insert "locking" the new thread into place. Really neat design but not perfect for a Subaru block.
Timesert part number is 1112 (M11X1.25) and it was $100 on Amazon.

In reply to fornetti14 :

I understand this is a very old thread, but the OP offered some critical information that proved very useful to me. I would also like to add some additional details that has changed the last few years to help with this fix. Since the last posting, Time Sert has created a kit specifically for Subaru head bolt threads, kit #11125. It includes all the tools needed to repair and install a Time Sert into the recessed holes of the Subaru block. The caveat to this is that the kit is VERY expensive, priced around $450. And the problem I've run into is none of the shops in my area have it, leaving me little option except to buy it or keep calling machine shops until I find one with it.

When I stumbled on this post, I realized there may be a very feasible and much more cost effective option to doing this. The OP mentioned in his last post that his fix wasn't exactly "perfect" for the Subaru block, but seemed to work. The kit he referenced (#1112) has a 22mm long insert, which is considerably shorter than the threaded portion of the block (30mm). Also, he had to grind the flange off the top of the insert in order for it to work. With the new kit, Time Sert has created a longer insert (30 mm) that does not have a flange (#51125). The inserts can be purchased separately, and are available individually or packages of 10.

So I'm planning to pick up kit 1112 and order a few of the longer inserts to see if I can get a solid repair for much less money. To the OP, I have a few questions for you so I'm hoping you're still active here.

Below is a link to Time Sert's page for the new kits:

http://www.timesert.com/html/universalheadbolt.html

I have successfully Helicoiled a Subaru engine.  Used two coils per hole and made an installation tool out of a piece of round stock and ten seconds on a grinder.

The recommended repair for the Cadillac Northstar was the Timesert.   Now there was some head problems, and it seemed to work.

Knurled. said:

I have successfully Helicoiled a Subaru engine.  Used two coils per hole and made an installation tool out of a piece of round stock and ten seconds on a grinder.

This sounds scary. If they aren't installed at the same time, it seems like the upper one could end up indexed different than the one below it, such that the bolt wouldn't engage the second part. How did you get around that?

In reply to kb58 :

What do you mean by "indexed"?  You drill out the hole, use the Helicoil tap to cut new really big threads, then thread in the Helicoil.  There's nothing to get out of sync because they are all in the same outer threading.

Not a problem, I have stacked helicoils many times.

As to helicoils pulling out the only time i have seen that happen is if they get stuck on a bolt that is being removed. I imagine that is possible with most any insert and would be highly dependent on the quality of the install.

Installed properly they increase the holding power of a thread by several orders of magnatude.

The only time a timesert is warranted is if there is repeated disassembly.

I use timeserts for spark plug repairs on aluminum heads. I like them there because they are locked into the parent material by swedging the flange.

Well, the concern here for using the timesert over the heli coil is the torque requirements for the ARP head studs I'm using.  While the studs themselves don't require any torque, the nuts fastening the heads in place are to be progressively torqued to 90 ft lbs.  That force is transferred through the threads of the studs and ultimately to the block.  And since the torque-to-yield bolts stretched when tightened, the stainless studs have no give.  This is the concern I have, and whether the heli coil will be ripped back out.  

If you're concerned, TimeCert it.